I was rightfully called out on the last graph - too little time and sloppy thinking. Here is the distribution of my sleep recordings. The purple bars show how what percent (of the 199 recordings) lasted within the six minute window of the x-axis. The orange cumulative line indicates the percent of daily sleep less than or equal to the hours shown - e.g., 81% of days, I slept less than 7.6 hours. Apparently I am a little more likely to sleep 6.2 or 6.7 hours than my average of 6.4.